This invention relates to flow control and, more particularly, to adaptations of Luer activatable and swabbable valves for the needleless control of fluids.
A valve is a device that controls flow, for example, in two directions. Where fluids need to be introduced into, or removed from, the body, it is common practice to do so through a flow control valve connected to a catheter, which is a slender hollow tube inserted into a body passage or cavity for passing fluids. A catheter permits the control of fluid flow both into and out of the body passage.
For example, medication can be injected into a flow control valve that is connected to the catheter. In prior practice, medication from a syringe has been introduced into the control valve using a needle, but this can be undesirable, since needle sticks are to be avoided. A number of attempts have been made to achieve the introduction of medication, or the extraction of fluid, without using syringes with needles.
Illustrative needleless valves are disclosed in Newgard et al., U.S. Pat. No. 5,064,416; Sivert, U.S. Pat. No. 4,915,687; Jackson, U.S. Pat. No. 4,429,856; Kilmarx, U.S. Pat. No. 3,352,531; Faust et al., U.S. Pat. No. 5,116,021 and Lynn, U.S. Pat. No. 5,549,651.
These arrangements typically have the objection that air borne and other pathogens can enter their inlets without being easily sterilized. While attempts have been made to maintain sterility by capping the inlets, the requirement of caps require open passages during connection, and additional complexity and expense. In addition, caps can become dislodged during storage and handling, rending the devices unusable or requiring special sterilization procedures.
Newgard '416 is representative in having a long inlet passage before there is access to a moveable member which is pierceable and controls flow by the extent to which a valving member can be dilated. Sivert, Johnson, Kilmarx and Faust are similarly objectionable.
Moreover, where valves are accessible by Luer fittings, instead of needles, the Luer fitting enters a long inlet passage before making contact with a moveable member that is unseated to permit fluid flow. Because of tolerance considerations, the inlet passage must be wide enough to accommodate the largest diameter Luer fitting. This means that for smaller diameter Luer fittings, within the tolerance specifications, there is a variable gap between the inlet wall of the valve and the Luer fitting being used to access the valve.
In the case of Lynn '651, no tolerance at all is provided, and a plug that is used to seal an input must be compressed in order to achieve operation.
The result typically is a substantially large area for contamination by pathogens that cannot be neutralized by swabbing of the valve, or, as in Lynn the need to compress a press-fit plug.
Accordingly, it is an object of the invention to overcome the problem of pathogen contamination that arises because of the need for valve inlets to accommodate a wide variety of Luer fitting diameters within the tolerance specifications that apply to such fittings.
Another object is to overcome pathogen contamination without requiring a press-fit plug that requires compression.
Still another consideration is desire to operate flow control devices with low "cracking" pressures, i.e. the pressure at which a control member moves away from its seat. For such devices, it is desirable to use relatively thin diaphragms. Unfortunately, thin diaphragms pose problems of stability. The diaphragm may move slightly away from its central position and become lodged against a side wall, causing a problem of leakage.
The catheters used with flow control valves are of various types. One type includes a tubular member for the introduction of fluids into a blood channel, which may be venous or arterial. Another type is a double-walled flexible tube which terminates at its outer end in two separate branches. One branch continues as an outer tube and terminates at its inner end in a inflatable portion.
The other branch continues as an inner tube with a through passage that extends to the inflatable portion of the outer tube. There are various other types of catheters as well.
With all types of catheters, it is desirable to be able to control the through flow of fluid using a suitable valve, which can be used in non-catheter applications as well.
Accordingly, it is another object of the invention to provide a miniature flow control valve which can be used without needles and is swabbable by being easily wiped with disinfectant across its inlet to eliminate contamination and pathogens. A related object is to allow the valve to be readily usable with devices, such as catheters, to control fluid flow while restricting operation by a patient or unauthorized personnel.
Still another object of the invention is to adapt needleless valves for use in branches of fluid feed systems, such as those which have plural sites for the introduction of fluids.
A further object of the invention is to provide a simple and expendable valve, which can be mass produced, readily assembled and provide ease of operation.
In the attempt to produce a swabbable needleless valve disclosed in Lynn U.S. Pat. No. 5,549,651, issued Aug. 21, 1996, a cylindrical piston with a slit extends from the proximal end of a tubular housing. When the cylindrical piston is sized to be tightly received within a cylindrical bore to effectively sealingly wipe the cylindrical side walls, the slit cannot be opened. If the piston is not tightly received, pathogens can enter the space between the cylindrical side walls and the piston.
Accordingly, a still further object of the invention is to overcome the objections presented by swabbable needleless valves of the Lynn type.